Lab 5G: How Transformers Work

TEKS
Name ___________________________ Class ________ Date ___________
Physics
Lab Investigation 5G
TEKS 5G Investigate and describe the relationship between electric and
magnetic fields in applications such as generators, motors, and transformers.
Descriptive
Lab 5G: How Transformers Work
Large transformers help electricity get from a generating plant to your home. Small transformers help you
charge electronic devices. In this activity you will investigate the relationship between electric and
magnetic fields by making a model of a transformer.
Materials
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1 plastic drinking straw
2 spools of thread
3 small paper cups
5 15-cm pieces of string
1 2-inch square of modeling clay
tape
marker
Procedure
1. Fold the drinking straw into a square. Crease the corners so the square can hold its shape.
2. Unfold the straw. Slide the spools onto the straw.
3. Fold the straw back into a square, making sure the spools are on opposite sides of the square.
4. Use the tape and marker to label the spools “Coil A: 600 coils” and “Coil B: 300 coils.” Label the
cups “Voltmeter A,” “Voltmeter B,” and “Voltage Source.”
5. Use small pieces of modeling clay to attach two pieces of string to Coil A and two pieces of string to
Coil B.
6. Take the free ends of the strings attached to Coil A. Use small pieces of modeling clay to attach the
ends of the strings to Voltmeter A.
7. Take the free end of one of the strings attached to Coil B. Use a small piece of modeling clay to attach the end of the string to Voltmeter B.
8. Take the free end of the other string attached to Coil B. Use a small piece of modeling clay to attach
the end of the string to the Voltage Source.
9. Use small pieces of modeling clay and the last piece of string to connect the Voltage Source to Voltmeter B.
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Name ___________________________ Class ________ Date ___________
TEKS
Physics
Lab Investigation 5G
Analyze and Conclude
1. In your model, is Coil B the primary coil or the secondary coil? How do you know?
Descriptive
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2. The number of loops in the primary coil divided by the number of loops in the secondary coil equals
the voltage in the primary coil divided by the voltage in the secondary coil. If the voltmeter attached
to the primary coil read 100 volts, what would the voltmeter attached to the secondary coil read?
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3. What part of the transformer does the straw represent, and how does this part transfer energy from
one coil to the other?
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